Whenever I receive an invitation in Outlook from another user on my Zimbra server, I check my calendar before accepting the invitation, and the event shows up as tentative. I go back into my mailbox and click "accept", then go back to my calendar, and it's gone! If I accept the invitation in the web client instead of in Outlook, it works and downsyncs correctly to Outlook. I wasn't having this problem when we first started using Zimbra a month ago. We're using 3.1.1, and I upgraded to the newest version of the Outlook Connector to see if that would fix it, but to no avail. Can anyone help me figure out what's going on?